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Prevalence and antimicrobial susceptibility of extended-spectrum b-lactamases-producing Escherichia coli isolates from community-acquired urinary tract infections in Madrid, Spain

Abstract number: 1733_67

Tamayo J., Orden B., Cacho J., Cuadros J., Gómez-Garcés J.L., Alós J.I.

Objectives: To assess the prevalence and monitor antimicrobial susceptibility trends of extended-spectrum b-lactamases (ESBL)-producing Escherichia coli isolates causing community-acquired urinary tract infections in 4 Health Care Areas of Madrid, Spain: Getafe, Argüelles, Alcalá de Henares and Móstoles.

Materials and Methods: A total of 6,721 E. coli isolates were recovered from November 2005 to June 2006. Of these, 279 unique ESBL-producing E. coli strains were studied. Antimicrobial susceptibility testing was performed by the agar dilution method according to guidelines of the CLSI. Thirteen antimicrobial agents were tested (see Table). Differences in antimicrobial susceptibility related to age distribution and gender were investigated.

AntibioticMIC (mg/L)%S%I%R
RangeMIC50MIC90 
Ampicillin>16>16>1600100
Cefazolin>16>16>1600100
Cefuroxime>16>16>1600100
Cefotaxime1–>16>16>16100
Amox/clav4/2–>32/168/432/1656.329.614
Piper/taz<=1/4–>64/44/432/477.117.95.0
Imipenem<=0.06–0.120.250.510000
Ertapenem<=0.008–0.120.030.0610000
Gentamycin<=0.5–>8<=0.5>881.32.216.5
Amikacin<=1–>162899.309.7
Fosfomycin<=1–>6421693.606.4
Ciprofloxacin<=0.06–>4>4>415.52.582.0
Co-trimoxazole<=0.5/9.5–>2/38>2/38>2/3837.362.7

Results: The table displays the susceptibility of ESBL-producing E. coli isolates to the 13 antimicrobial agents tested. The point prevalence of ESBL-producing E. coli was 4.15% (279/6,721) overall, 5.97% (56/938) in Getafe, 3.94% (75/1,903) in Argüelles, 3.60% (74/2,057) in Alcalá de Henares, and 4.06% (74/1,823) in Móstoles.

No difference was found in antibiotic susceptibility patterns with patients' gender. However, pathogens resistant to co-trimoxazole or ciprofloxacin were detected less frequently in patients aged <50 years than in patients aged ≥50 years (for co-trimoxazole, OR = 0.43, 95%CI: 0.20–0.93, p = 0.018; for ciprofloxacin, OR = 0.32, 95%CI: 0.14–0.74, p = 0.0027).

Conclusions: ESBL-producing E. coli isolates were highly prevalent among patients with community-acquired UTI. All strains tested were susceptible to carbapenems. Ertapenem was the most active agent tested, with an MIC90 of 0.06 mg/L, followed by imipenem (MIC90, 0.5 mg/L), amikacin (MIC90, 8 mg/L), and fosfomycin (MIC90, 16 mg/L). Ciprofloxacin and co-trimoxazole exhibited the lowest activity; isolates from patients aged ≥50 years were more often resistant than those isolated from younger patients.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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